N = 2*10**5
mod = 998244353
g1 = [1]*(N+1) # 元テーブル
g2 = [1]*(N+1) #逆元テーブル
inverse = [1]*(N+1) #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1[i]=( ( g1[i-1] * i ) % mod )
    inverse[i]=( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2[i]=( (g2[i-1] * inverse[i]) % mod )
inverse[0]=0

def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return (g1[n] * g2[r] % mod) * g2[n-r] % mod



import sys,random,bisect
from collections import deque,defaultdict
from heapq import heapify,heappop,heappush
from itertools import permutations
from math import log,gcd

input = lambda :sys.stdin.readline()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

N,M = mi()

res = 0
for k in range(1,min(M,N+1)+1):
    if k==1:
        res -= cmb(M,k,mod) * pow(M-1,2*N,mod) % mod
    else:
        
        res -= cmb(M,k,mod) * pow(k,k-2,mod) * g1[N] * g2[N-k+1] * pow(2,k-1,mod) * pow(M-k,2*(N-(k-1)),mod) % mod
    
    res %= mod

res += M * pow(M,2*N,mod) % mod
print(res % mod)